Had a melonited 16" free floated 300BLK upper with quad rail that I paired with a basic Palmetto State Armory lower and an AIM Surplus Nickel Boron BCG that I sold for $625. leaving me about $100 after paying for the Grendel. I then sold off one of my (many) Vortex dots and a magnifier, that put me within $125 of this when it was on sale for $399 including BCG and charging handle plus a $10 off coupon!):

Hardened Arms Stainless 16" 300 AAC Blackout Upper

That one is paired with a PSA lower with an FDE BCM Stock and grip. My goal is to eventually replace the chunky quad rail for a lighter FDE hybrid or keymod rail for it. I havea a Vortex Diamondback 3-9x40 for it and, since I plan to make this a multipurpose weapon, intend to eventually mount a small red dot on top and possibly a laser on the side.

Plan to use it mostly as a tree stand gun for deer.